Make 'svn merge' print the conflict summary before showing output from the conflict resolver, and also restrict post-merge interactive resolution to paths which got new conflicts flagged during the merge operation.
Corresponds to changes made for 'svn update' in r1357298 and r1357313.
* subversion/libsvn_client/merge.c (merge_dir_props_changed, merge_file_changed): Invoke the conflict callback from the client context again. (merge_locked, merge_peg_locked, do_symmetric_merge_locked): Stop resolving conflicts before returning.
* subversion/svn/merge-cmd.c (svn_cl__merge): Postpone conflict resolution during the merge operation. Run the conflict resolver on any paths which got conflicts flagged during the merge operation.